This invention relates generally to the field of fans and, more particularly, to portable fans of the type used in firefighting applications by the use of positive pressure ventilation to help the firefighter both clear smoke from his path and fight the fire.
Positive pressure ventilation is a firefighting technique for removing heat and smoke from a fire area within a building or the like wherein clear air is directed into the building to produce a positive pressure therein by using fans, or blowers. This technique is becoming well known in the art and involves, by way of example, positioning the fan in or near a ground floor doorway of a house having a fire therein and breaking open a window at a desirable location on the other side of the fire, such as on the second floor. The fan is operated to blow air into the house to create what is called a "positive pressure" inside the house (typically a couple inches of water pressure) which pushes the smoke out. By the proper selection of the location of the exit opening and the direction of air flow from the fan, the clear air will flow from the doorway across the fire area to move smoke away from the fire area so that it rises up and out of the house and away from the firefighters through the second floor opening provided.
There are two types of blowers in use today for this type of firefighting application, namely, electric blowers and gasoline-powered blowers. Electric blowers have the disadvantage that for portable construction the higher horsepower motors are two heavy and cannot provide the high power requirements for many applications. Also, electric blowers normally are limited in speed to 3600 RPM. Gasoline-powered blowers have the disadvantages that the are noisy, heavy, and introduce harmful carbon monoxide inside the structure where the fire is located.
It is the general object of the invention to provide a fan system of the indicated type which obviates the problems of the electric and gasoline-powered blowers in use today by providing a clean operation and by providing sufficient power with light weight and portability for any firefighting application.
Another object of the invention is to provide a fan system of the indicated type wherein the fan uses a water powered turbine as its driver.
Another object of the invention is to provide a portable fan system of the indicated type which is capable of ventilating smoke and fumes and cooling a building having a fire therein.
Another object of the invention is to provide a fan system of the indicated type wherein the fan is constructed so that it is easy to stow, is portable and is easy to set up and use.
Another object of the invention is to provide a fan system of the indicated type which can act like a mobile sprinkler system by delivering a water spray or mist onto the fire area to provide a cooling air stream.
Another object of the invention is to provide a fan system of the indicated type including a flow control means for setting the system to operate in a plurality of modes, including a mode wherein a clear air stream is directed toward the fire, a mode wherein an air stream and a mist is directed toward the fire, and a mode wherein a straight fire stream is directed toward the fire.
One of the important advantages of the system in accordance with the invention is that by using a water powered turbine as the driver of the fan, it is possible to provide an extremely small and compact power source for the fan. For example, a 20 horsepower aluminum water turbine weighs only about 20 pounds whereas a 20 horsepower gasoline engine weighs over 100 pounds. Thus, the device in accordance with the invention can be made portable so that it can be set up quickly and easily and so that the firefighter can more easily carry the fan with him as he advances towards the fire. Also, the high speed fan design in accordance with the invention is made to provide a very high volume of flow with a very light and compact construction by using a lightweight aluminum housing and strong lightweight fan blades. Thus, the device can be designed to be sufficiently portable so that one man can carry it and, in use, there is a valve attached so that whenever the firefighter reaches an area of the fire where the fumes and smoke have been evacuated he can open a valve and direct a stream of water directly onto the fire using the water supply line that was driving the fan.
As to other prior art, there is in use a smoke and fume extractor especially developed to extract fumes or to ventilate rooms subject to explosion dangers. This device utilizes a vacuum fan driven by a water turbine to pull smoke and fumes from a danger area.